Heretofore, a method for manufacturing a three-dimensional shaped object by irradiating a powder with a light beam has been known (such method can be generally referred to as “selective laser sintering method”). Such method can produce a three-dimensional shaped object with a plurality of solidified layers stacked integrally by repeating the step (i) of forming a solidified layer by irradiating a predetermined portion of a powder layer with a light beam, thereby allowing sintering of the predetermined portion of the powder or melting and subsequent solidification thereof, and the step (ii) of forming another solidified layer by newly forming a powder layer on the resulting solidified layer, followed by similarly irradiating the powder layer with the light beam (see JP-T-01-502890 or JP-A-2000-73108). The three-dimensional shaped object thus obtained can be used as a metal mold in a case where inorganic powder materials such as a metal powder and a ceramic powder are used as the powder material. While on the other hand, the three-dimensional shaped object can be used as a model or replica in a case where organic powder materials such as a resin powder and a plastic powder are used as the powder material. This kind of technology makes it possible to produce the three-dimensional shaped object with a complicated contour shape in a short period of time.
In most cases regarding the selective laser sintering method, the manufacturing of the three-dimensional shaped object is performed under an inert atmosphere in a chamber to prevent an oxidation of the shaped object. Within the chamber, a base plate is disposed on a forming table, and the base plate is secured to the table by means of a bolt. Thereafter, the three-dimensional shaped object is manufactured on the bolted base plate. By way of the case of using a metal powder as a powder material and using the resulting three-dimensional shaped object as metal mold, as shown in FIG. 1, a powder layer 22 with a predetermined thickness “t1” is firstly formed on the base plate 21 (see FIG. 1(a)) and then a predetermined portion of a powder layer 22 is irradiated with a light beam to form a solidified layer 24 on the base plate 21. Then, a powder layer 22 is newly provided on the solidified layer 24 thus formed and is irradiated again with the light beam to form another solidified layer. In this way, the solidified layer is repeatedly formed, which leads to a provision of a three-dimensional shaped object with a plurality of solidified layers 24 stacked integrally (see FIG. 1(b)). The solidified layer corresponding to a bottom layer can be formed in a state of being adhered to the surface of the base plate. Therefore, the three-dimensional shaped object and the base plate are mutually integrated. The integrated “three-dimensional shaped object” and “base plate” can be used as a metal mold as they are.